1. Field of the Invention
The present invention relates to a device for inserting a deformable intraocular lens into the eye. Examples of such a deformable intraocular lens include a deformable intraocular lens that is inserted into the eye in place of the natural lens when the latter is physically extracted because of cataracts, and a vision correction lens that is inserted into the eye for the sole purpose of vision correction.
2. Description of the Related Art
In general, during cataract surgery, an intraocular lens is inserted into the eye, from which the natural lens has been removed (lens-removed eye), such that the intraocular lens is located in the original position previously occupied by the natural lens and restores vision. Various studies on the material and shape of such an intraocular lens have been carried out since Ridley performed the first implantation of an artificial lens in 1949.
In recent years, in addition to studies on intraocular lenses which are used for vision restoration after cataract surgery, intense studies on intraocular lenses for refractivity correction have been ongoing. Such an intraocular lens for refractivity correction is inserted into the eye which still has a natural lens (lens-carrying eye), for correction of nearsightedness or farsightedness.
In relation to cataract surgery, a technique for crushing the lens tissue by means of ultrasonic emulsification and suctioning the crushed tissue away has been popularized. This technique enables performance of lens removal surgery to excise an opaque lens through a small incision. Along with progress in the operational technique itself, intraocular lenses themselves have recently been improved. Such an improved intraocular lens is disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 58-146346. In the intraocular lens, the optical portion is made of a deformable elastic material. The intraocular lens is inserted, in a folded state, into the eye through a small incision and restored to its original shape within the eye, allowing it to exert its proper lens function.
Accompanying these technical developments, the material of the optical portion of such an intraocular lens has been changed gradually from hard polymethyl methacrylate (PMMA) to silicone or soft acrylic resin, which enables the intraocular lens to be inserted into the eye in a folded state.
Moreover, in recent years, studies have been conducted on copolymers such as hydroxyethyl methacrylate and methyl methacrylate, as well as on hydrophilic materials such as 2-hydroxyethyl methacrylate (HEMA). Further, intraocular lenses of different shapes have been studied and put into practical use, including an intraocular lens having a circular optical portion and loop-shaped support portions formed of different materials, an intraocular lens whose loop-shaped support portions and optical portion are formed of the same material, and an intraocular lens having plate-shaped support portions. Furthermore, Japanese Kohyo (PCT) Patent Publication No. 9-506285 discloses an insertion device for inserting the above-described deformable intraocular lens into the eye in a compressed or folded state. In the intraocular-lens insertion device, a lens is held in a stress-free state in an intermediate preparation region, and the intermediate preparation region is attached to the main body. After attachment of a cannulae (insertion tube), the intraocular lens is inserted into the eye through the cannulae. The intermediate preparation region serves as a lens package.
Moreover, there has been proposed an invention in which a viscoelastic material (a lubricant for an intraocular lens) is injected into the intermediate preparation region through a hole optionally provided in a lens receiving portion which constitutes the intermediate preparation region.
<Problems to be Solved by a First Aspect of the Invention>
However, since a mark for indicating an injected quantity is not provided, a user encounters difficulty in grasping the charged quantity. Therefore, the user may inject the viscoelastic material in an excessive quantity, thereby increasing operation costs. In addition, when the injected quantity is insufficient, a sufficient lubricating effect cannot be attained, resulting in occurrence of troubles such as breakage of an intraocular lens. Moreover, since the viscoelastic material is used as a lubricant which enables smooth passage of an intraocular lens through the cannulae (insertion tube), the viscoelastic material is desirably injected on the side toward the cannulae (insertion tube) with respect to a lens placed in the intermediate preparation region. However, in the invention, since a hole for injecting the viscoelastic material is formed in the lens reception portion of the intermediate preparation region so as to be perpendicular to the center axis of the cannulae (insertion tube), a user encounters difficulty in controlling the direction of injection from the hole, resulting in failure to inject the viscoelastic material to the cannulae (insertion tube) side at which the viscoelastic material is needed for smooth passage of the lens or resulting in accidental injection of the viscoelastic material to the rear of the intermediate preparation region at which injection of the viscoelastic material is unnecessary, thereby increasing operation costs.
Meanwhile, the insertion device proposed in Japanese Kohyo (PCT) Patent Publication No. 9-506285 has the following drawbacks. Although the intermediate region of the device can be used as a lens package, work for attaching a cannulae (insertion tube) to the main body must be performed during actual use, because the cannulae (insertion tube) is a member which is formed separately from the main body. Although a technique for storing an intraocular lens in advance at the intermediate region located on the center axis of a push rod has been proposed, the intermediate region is difficult to form from a material suitable for storing the lens. In addition, the intermediate region cannot be formed to have a function necessary for properly holding an intraocular lens having loop-shaped support portions. That is, although such an intraocular lens must be stored in a state in which the angle between the optical portion and the support portions of the intraocular lens is maintained, the intermediate region of the conventional insertion device cannot provide such an angle-maintaining function. In order to solve the above-described problems, the assignee of the present invention has proposed an insertion device for an intraocular lens which simplifies operation (see Japanese Patent Application Laid-Open No. 2001-104347).
Specifically, in the proposed insertion device, an intraocular lens is stored in a lens-holding member of an insertion device; and when the lens is used, the lens is moved and set to a predetermined position by means of a lens-moving mechanism. Thus, the intraocular lens can be stored in a state in which no stress acts on the optical portion and the angle of the support portions is maintained, to thereby eliminate the necessity of a conventionally-used lens case having a mechanism for maintaining the angle of the support portions of an intraocular lens. Further, the insertion device eliminates or simplifies an operation of placing a lens on an insertion device, thereby saving the time involved in the placement operation, while solving drawbacks involved in conventional insertion devices, such as breakage of a lens or improper insertion of a lens, which would otherwise be caused by improper operation by an operator. Moreover, the insertion device enables provision of an intraocular lens and an insertion device in a sterilized state.
<Problems to be Solved by a Second Aspect of the Invention>
However, the injection device disclosed in Japanese Patent Application Laid-Open No. 2001-104347 has the following drawbacks. When the moving mechanism is operated accidentally, an intraocular lens is unintentionally set to the predetermined position.
Further, in the course of transportation, the moving mechanism may operate as a result of vibration or shock to thereby move an intraocular lens from a standby position to the predetermined position. Moreover, when a user injects a lubricant into the insertion tube from an open end of the insertion tube or a separately provided injection passage by use of, for example, a syringe, the user encounters difficulty in performing such operation with adequate visual observation, because the insertion tube and the injection passage are very small.
Moreover, since an insertion device for an intraocular lens is designed to pass a deformed intraocular lens through the insertion tube and push the lens into the interior of the eye from a tip end of the insertion tube inserted into a small incision formed on the eyeball, the insertion tube has a very small wall thickness and therefore deforms easily upon receipt of external force. Therefore, the insertion tube must be handled with care.